Dual dependency represents a specific case of dependency. The term dual dependency covers such cases in which a modification (both valency and non-valency) has a dual semantic dependency relation, i.e. it simultaneously modifies a noun and a verb (which can be nominalized). The dependency on a noun is often expressed also formally (by agreement in the grammatical categories).
We distinguish these two cases:
dual dependency of a free modification - predicative complement (see Section 10, "Predicative complement (dual dependency)").
We represent the two dependency relations of an adjunct in the predicative complement position by an edge (dependency on the verb) and by an attribute of the type reference: compl.rf (dependency on the noun). For more on representation of the dual dependency of predicative complements see Section 10, "Predicative complement (dual dependency)".
dual dependency of an argument.
Valency modifications (both prepositional and non-prepositional) with a dual dependency are represented as arguments of the governing verb and their functor is usually PAT or EFF (i.e. their dependency on the verb is represented by an edge); their dependency on the noun follows from the meaning of the verb, which is captured by its valency frame.
With modifications with a dual dependency expressed by a verb form, the grammatical coreference relations are also represented in the tree. For details see Section 2.3, "Coreference with verbal modifications that have dual dependency".